Upload
arnisadoryeskrimador
View
216
Download
0
Embed Size (px)
Citation preview
8/13/2019 Aplicaciones de la Fotnica de Microondas 1
1/13
1
Introduction
Departamento de ComunicacionesCurso de Doctorado
2004-2005
Aplicaciones de la Fotnica deMicroondas
Contents
Introduction
Concept of photonic processing of RF signals
Potential applications
Advantages Examples of applications:
Mobile, wireless and RoF
Antenna beamsteering
Radars
Optical prefiltering of SCML
8/13/2019 Aplicaciones de la Fotnica de Microondas 1
2/13
2
CURRENT EUROPEAN PROJECTS
IST-2001-37435 Lightwave Architectures forthe Processing of Broadband ElectronicSignals (LABELS)
IST-2001-32786 Network of Excellence on
Broadband Fiber Radio Techniques and its
Integration technologies (NEFERTITI)
Introduction
In RF systems it is interesting to use photonic devices toimplement flexible filters for microwave and radiofrequency(RF) signals free from bandwidth constraints
This involves using photonics technology and devices toperform the required signal processing tasks over RF signals
conveyed by an optical carrier directly in the optical domain. Also there is an increased use of the RF and microwave
spectrum apart from baseband within optical channels inWDM systems and a need to access or process them directlyin the optical domain
Thus there are two main driving application fields
RF systems and applications
Optical Transmission systems and networks
8/13/2019 Aplicaciones de la Fotnica de Microondas 1
3/13
3
RF circuit
antenna
Rf input
signalRf output
signal
Optical
CW source
Rf input
signal
Optical Signal
Processormodulator
Optical
Receiver
Rf output
signal
Optical
output
signal
Optical
input
signal
antenna
TRADITIONAL APPROACH
Band limitation
Poor flexibility
EMI
Frequency dependent losses
PHOTONIC SOLUTION
OPRFS (Optical Processing
of RF Signals)
Incoherent regime (tc
8/13/2019 Aplicaciones de la Fotnica de Microondas 1
4/13
4
Introduction: What for? (II)Optical Transmission
The concept of photonic processing of RF signals for opticalTransmission systems and networks
To headerprocessingInput multiwavelength
SCM signal
Payload CH#1
Payload CH#N
Header CH#1
Header CH#N
Photonic
Filter
Baseband
Signals
Improve performance of Radio over Fiber systems
Payload and header separation in Label swappingoptical networks
Pilot tone extraction within WDM channels for control,
protection and management purposes Service separation in WDM transmission carrying
multiple RF services within an optical wavelength.
Potential Applications
Introduction: What for? (II)Optical Transmission
8/13/2019 Aplicaciones de la Fotnica de Microondas 1
5/13
5
Introduction: Advantages
Optical delay lines have very low loss (independent ofthe RF signal frequency),
ODLs provide very high time bandwidth products
Are immune to electromagnetic interference (EMI).
Lightweight
Can provide very short delays which result in very highspeed sampling frequencies (over 100 GHz in
comparison with a few GHz with the available electronictechnology)
Optics provides the possibility of spatial and wavelengthparallelism using WDM techniques.
Examples of applications
Radio
Microwaves
IREHFSHFUHFVHFHFMFLFVLFELF IR
1 KHz 1 MHz 1 GHz 1 THz
1 m1 km1000 km 1 mm 1 m
KXCSL
Mobile, ROF& Wireless Coms
Satellite
Radar
mm and sub THzImaging and sensing
8/13/2019 Aplicaciones de la Fotnica de Microondas 1
6/13
6
Examples of applications
Photonic filters can be applied: For channel rejection
For channel selection applications
Directly in the RF domain with no required previousdown-conversion
In the first case, we deal with an optical link where notonly the desired signal is carried by the fiber, but alsounwanted interfering signals that are also picked up by
the antenna. Example: radio astronomy applications the signal transmission
from several stations to a central site requires the removingstrong man-made interfering signals from the astronomy bands.
Noise suppression and channel interference mitigation in thefront-end stage after the receiving antenna of i.e an UMTS basestation prior to a highly selective SAW filter.
Mobile, Wireless & Radio over Fiber Systems
In the second case, the signal carried by the optical linkis composed of a frequency plan that comprises severaldisjoint parts of the RF spectrum (UMTS, HIPERLAN,LMDS) .
A band-pass photonic filter can be employed to select a givenRF band or spectral region
Or for noise suppression and channel interference mitigation.
In both cases the position of the frequency notch or thefilter band-pass can be as low as a few MHZ or as highas several tens of GHz due to the broadbandcharacteristics of photonic delay lines.
Mobile, Wireless & Radio over Fiber Systems
Examples of applications
8/13/2019 Aplicaciones de la Fotnica de Microondas 1
7/13
7
RF Photonics
Notch/bandpass
filter
Downconversion
DSP
Down
conversionADC DSP
ADC
Less stringentrequirements
Mobile, Wireless & Radio over Fiber Systems
Examples of applications
RF in
FBG 1 FBG N
L 2L 4L
Optical
switchesRFout
DispersiveMedia
SSMF or DCF
8L
EOMSLD
Detector
1540 1545 1550 1555 1560 1565 1570 1575
-35
-30
-25
-20
-15
-10
-5
0
30 UFBG 1nm wavelength spaced
FBG array spectrum ->
MWP tuneable filter for UMTS applications
App licati on: Tunable photonic filter for noise suppression and channel interference mitigation in thefront-end stage of a UMTS base station. The inclusion of such a filter can increase the capacity ofUMTS systems. Objectives: a) High Q factor (select 1 UMTS channel 5MHz at 2 GHz), Tunability,Realizable cost.
Design of UMTS microwave photonic filter:1. Classical FIR transversal but combining some different techniques.2. Spectral slicing of a high power broadband optical source to obtain an equivalent multi-
wavelength source.3. Slicing by an array of fibre Bragg gratings which also introduces a fixed time delay between the
reflected slices.4. Finally, we employ a reconfigurable chain of dispersive modules to introduce tunability.
D. Pastor et al, Electron Lett. vol. 4, no 16, August 2004.
Radio over Fiber Systems
Examples of applications
8/13/2019 Aplicaciones de la Fotnica de Microondas 1
8/13
8
MWP tuneable filter for UMTS applicationsRequirements: High Q-factor (about 400) & Tunability of the RF passband within the 12 channels
along the 60 MHz band.1. The transversal filter operates at a higher-order resonance of its periodic response. (we employ
the resonances n18 to reduce the required number of samples. The FSR of the filter has beenset to 109 MHz, and the corresponding spacing between the (adjacent) gratings was 930 mm.
2. Other goals: 3 dB bandwidth within 56 MHz, a 1 dB bandwidth larger 3 MHz, and anacceptable sidelobe rejection level (>20 dB). Gaussian apodisation of the taps weights wasemployed, and the total number of FBGs was fixed to 30. The FBG wavelength spacing wasset to 1 nm to allocate properly the FBG along the SLED spectrum (40 nm).
1 . 8 1 . 8 5 1 . 9 1 . 9 5 2 2 . 0 5 2 . 1
x 1 09
-2 0
-1 8
-1 6
-1 4
-1 2
-1 0
-8
-6
-4
-2
0
0 km10.7 km
Frequency (GHz)
(dB)
FSR=1977MHz/18=109MHz
17th 19th18th
Radio over Fiber Systems
Examples of applications
1.93 1.94 1.95 1.96 1.97 1.98 1.99
-18
-16
-14
-12-10
-8
-6
-4
-2
0
Frequency(GHz)
0 2 4 6 8 10 121.935
1.94
1.945
1.95
1.955
1.96
1.965
1.97
1.975
1.98x 10
9
Standard Fibre Length (km)
-30
-20
-10
0
1.85 1.90 1.95 2.00 2.05 2.10
f (GHz)
>22dB
RFResonacefrequency
MWP tuneable filter for UMTS applications
Slope of 3.577 MHz / km(i.e. 1.39 km fibre is requiredfor the shift of 5 MHz).
Coverage of the UMTS band v.s. the length of theSMF-28 fibre used as dispersive medium.
1.80 1.85 1.90 1.95 2.00 2.05 2.10 2.15
-40
-30
-20
-10
0
Transferfunction(dB)
dB21MSLR
353Q
MHz6.5f
MHz44.1976f
dB3
o
=
=
=
=
MeasuredSimulated
Radio over Fiber Systems
Examples of applications
8/13/2019 Aplicaciones de la Fotnica de Microondas 1
9/13
9
Multifrequencysource
1, 2,........NOptical carriers
RF signalgenerator
Amplitude modulatorFiber BraggGrating
1
2
= 2 1
WDM
d1
(1,1)2
(2,2)
(,)i
(i,i)
ArrayAntenna
( ) ( ) ( )[ ]10 = iid
csin
( ) ( )
+
==
sindc
iii
j
eN
i ii
EAF
,1
0
,
( )=
RF
Antenna beamsteering
Radiation
pattern
Modulating RF signal: RF Optical carrier: B
Non-uniformFBGLeff
BOptical fiber
B. Ortega et al.,IEEE Trans. onMTT, 48 pp.1352-1360 (2000).
Examples of applications
Intensidad (dB)-40 -30 -20 -10 0-40-30-20-100
ngulo (grados)
-80
-60
-40
-200
20
40
60
80
(a)
Intensidad (dB)-40 -30 -20 -10 0-40-30-20-100
ngulo (grados)
-80
-60
-40
-200
20
40
60
80
(b)
Intensidad (dB)-40 -30 -20 -10 0-40-30-20-100
ngulo (grados)
-80
-60
-40
-200
20
40
60
80
(c)
Intensidad (dB)-40 -30 -20 -10 0-40-30-20-100
ngulo (grados)
-80
-60
-40
-200
20
40
60
80
(a)
Intensidad (dB)-40 -30 -20 -10 0-40-30-20-100
ngulo (grados)
-80
-60
-40
-200
20
40
60
80
(b)
Intensidad (dB)-40 -30 -20 -10 0-40-30-20-100
ngulo (grados)
-80
-60
-40
-200
20
40
60
80
(c)
Intensidad (dB)-40 -30 -20 -10 0-40-30-20-100
ngulo (grados)
-80
-60
-40
-200
20
40
60
80
(a)
Intensidad (dB)-40 -30 -20 -10 0-40-30-20-100
ngulo (grados)
-80
-60
-40
-200
20
40
60
80
(b)
Intensidad (dB)-40 -30 -20 -10 0-40-30-20-100
ngulo (grados)
-80
-60
-40
-200
20
40
60
80
(c)
0 43.6 80
2 GHz
4 GHz
7 GHz
DSB modulation: 32 elements, d = 21.4 mm (fmax = 7 GHz)
Wideband operation: 2 - 7 GHz
Stable beampointing angle
Spatial range: 0 - 90 with continuous tuning angle
DSB modulation : 32 elements, d = 21.4 mm (fmax = 7 GHz)
Wideband operation: 2 - 7 GHz
Stable beampointing angle
Spatial range: 0 - 90 with continuous tuning angle
SSB modulation : 32 elements, d = 8.3 mm (fmax = 18 GHz)
Larger wideband operation : 4 - 18 GHz (C-X-Ku)
SSB modulation: 32 elements, d = 8.3 mm (fmax = 18 GHz)
Larger wideband operation : 4 - 18 GHz (C-X-Ku)
Antenna beamsteering
Examples of applications
8/13/2019 Aplicaciones de la Fotnica de Microondas 1
10/13
10
Clutter Elimination at RF in MTI Radars
PRF
Landclutter
Landclutter
Target
Seaclutter
Rainclutter
Noise PRI
=1/PRF
Doppler shift=-(2/)(dR/dt)
R(t)=
Ro+d
R/dt(
t-to)
MTI: Moving Target Indicator Radaruses Doppler effect to separate
targets of interest from clutter
Examples of applications
Clutter Elimination at RF in MTI Radars
Downconversion
A/DDigitalNotchfilter
Filtering of clutter and noise is performed using a digitalnotch filter placed after frequency down-conversion tobase-band and analogue to digital (ADC) conversion.
To distinguish the small echo from the target from largeecho from the fixed objects high performance (14-18 bitresolution) ADCs are required which represents a majorbottleneck in the system
Examples of applications
8/13/2019 Aplicaciones de la Fotnica de Microondas 1
11/13
11
Clutter Elimination at RF in MTI Radars
If the clutter can be removed directly in the opticaldomain by means of a photonic filter, then the highresolution requirements on the ADCs can be relaxed.
For example, with a 30 dB clutter attenuation therequired ADC resolution is reduced by 5bits.
RF Photonics
Notch/bandpass
filter
Downconversion
A/D DSP
Examples of applications
Al l-Opt ical Microwave Inter ference Mit igation Fil ter Single Bandpass filter
Port 4
EOM
LCA
Fiber length
RF signal
TunableLaser
Port 1 Port 2
L
PL(-L)
Port 3
1520 1560-80
-60
(a)
S(dBm)
(nm)
1530 1535
-60
-40
(c)
T(dBm)
(nm)
1530 1535
-60
-50
(b)
TSBF
(dBm)
(nm)
BroadbandOptical Source
OSA
OSA
0 5 1 0 1 5 2 00.0
0.5
1.0
1.5
2.0
M u lt i -No tc h
Re g io n
S in g le
Not ch
Re g io n
f3dB
f(GHz)
( n s )
7 8 9
-30
-20
-10
0
10
(a) n = 0
f (GHz)
|H
(dB)|2
7 8 9
(b) n = 22
f (GHz)
7 8 9
-30
-20
-10
0
10
(a) n = 52
|H(d
B)|2
f (GHz)
7 8 9
(b) n = 112
f (GHz)
Notch filters by combining a tunable laser and a broad band source sliced by a Mach-Zehnder interferometer for applications as interference mitigation filters.
Using a single bandpass filter centered at 7.89 GHz with a 3dB bandwidth of 250 MHz,single and multi notch filters have been implemented by tuning the optical wavelength of thetunable laser.
The single and multi-notch regions are given by the bandwidth of the single bandpass filter.
Notch filters by combining a tunable laser and a broad band source sliced by a Mach-Zehnder interferometer for applications as interference mitigation filters.
Using a single bandpass filter centered at 7.89 GHz with a 3dB bandwidth of 250 MHz,single and multi notch filters have been implemented by tuning the optical wavelength of thetunable laser.
The single and multi-notch regions are given by the bandwidth of the single bandpass filter.
f=280MHz f=67MHz
f=30MHz f=15MHz
for RADAR
applications
J.Mora et al.,Intl Topical Meetingon MWP, MC-12, pp.77-80 (2004).
Examples of applications
8/13/2019 Aplicaciones de la Fotnica de Microondas 1
12/13
12
Optical Prefiltering Using FBGs Rf photonic filters can also be used to extract a microwave
signal carried by an optical channel (wavelength). Thisapplication is known as OPTICAL PREFILTERING
fo fo+fRFfo-fRF
Optical filter
fo fo+fRFfo-fRF
fo
Examples of applications
Optical Prefiltering using an Uniform FBG
circulator
Payload
f
label
f
Payload
label
f RF
Through port
OSCM extraction
PortFBG filter
Lee et al IEEE PTL,vol13, pp. 635,2001
Optical Prefiltering Using FBGs
Examples of applications
8/13/2019 Aplicaciones de la Fotnica de Microondas 1
13/13
13
f
f
Lee et al IEEE PTL,vol13, pp. 635,2001
Channel payload @ 2.5 Gb/sChannel header @ 622 Mb/s anda subcarrier at 14 GHz
Optical channel before the FBG
Optical channel after the FBG
Optical Prefiltering Using FBGs
Examples of applications
Optical Prefiltering Using FBGs: IST LABELSexperiment at 10 Gb/s
f
f
622Mbps
10Gbps
fs=18GHz
OSALSA
FBG
Payload @10GbsHeader @622 Mb/s
Optical channel before the FBG
Optical channelafter the FBG